The preferred embodiments of the present invention generally relate to electrical sockets, such as pin grid array (PGA) sockets. More specifically, the preferred embodiments of the present invention generally relate to zero insertion force (ZIF) processor sockets.
Heretofore, PGA sockets have been proposed that include a base having a cover slidably mounted thereon. The sliding motion between the base and cover is controlled in numerous manners in conventional ZIF PGA sockets. For example, U.S. Pat. No. 5,256,080 discloses a bail actuated ZIF socket. U.S. Pat. No. 5,730,615 describes a ZIF PGA socket that uses a flat or plate tool that is inserted into receiving slots in the cover and base. The flat tool is moved between two positions in order to open and close the ZIF socket. U.S. Pat. No. 4,498,725 discloses a prior art PGA socket having a base housing and a moveable cover. An L-shaped lever moves the cover across a top surface of the housing. The lever includes a first arm that is rotatably received in a passage in the socket and a second arm that provides a handle for rotating the first arm.
However, existing ZIF sockets have experienced limited applicability to certain processor designs. For instance, many circuit designs are conditioned on PGA chips being arranged in a closely packed manner with respect to one another. For instance, at least one conventional socket uses an actuation lever located along one side of the socket and is moved in the same direction as the direction of relative movement between the cover and base housing. For instance, the lever is moved forward along the side of the socket to drive the cover forward and visa versa. However, as components decrease in size and are located closer to one another, space constraints no longer permitted the lever to be located along the side of the socket. Thus, it is desirable to minimize the width of sockets holding the PGA chips.
Also, as chip technology evolves, the number of pins on a single chip increases. The socket achieves a separate electrical contact with each pin on a chip and thus the number of electrical contacts to be maintained by a socket is increased. As the pin/contact count increases, the force required to electrically engage the chip and socket similarly increases. Conventional sockets focus significant actuation forces on small areas on the cover and housing. As the actuation forces increase, various socket designs experience more faults as the housing and cover are unable to withstand the increased loads. Conventional sockets for high pin count PGA chips do not spread actuation forces over the entire housing/cover.
A need remains for an improved socket. It is an object of the preferred embodiments of the present invention to meet this and other needs that will become apparent from the following description, drawings and claims.
In accordance with at least one preferred embodiment, a socket is provided for an electronic package. The socket includes a cover and base housing that are slidably engaged with one another. The cover and base housing are moveable between open and closed positions along a socket longitudinal axis. The socket further includes an actuation member configured to move the cover when the actuation member is rotated about a rotational axis. The actuation member is aligned such that the rotational axis of the actuation member is parallel to the socket longitudinal axis along which the cover and base housing move relative to one another. The actuation member drives the cover along the longitudinal axis between open and closed positions when the actuation member is rotated about the rotational axis.
In accordance with at least one alternative embodiment, the actuation member comprises a cam assembly slidably received within a journaled portion of the base housing. The cam assembly transfers rotary motion of the actuation member about the rotational axis to linear motion along the longitudinal axis. In accordance with at least one alternative embodiment, the cam assembly has at least one pusher bar mounted thereon. The pusher bar slidably engages the cover to drive the cover between open and closed positions. The cam assembly may include a plurality of pusher bars and the cover may include an equal plurality of slots slidably receiving the pusher bars. The pusher bars and slots are aligned at an angle to the socket longitudinal axis such that movement of the actuation member along a transverse axis in a direction at an angle to the socket longitudinal axis drives the cover along the longitudinal axis. The chamber in the base housing or cover may be located near the rear end thereof. The chamber includes tracks along opposite sides that receive a cam assembly included within the actuation member. The cam assembly is movable within the tracks laterally from one side to the other side of the base housing or cover.
In accordance with at least one alternative embodiment, the actuation member includes a lever having a handle and a leg. The leg includes an offset cam journal movable along an arcuate path when the handle is rotated about the rotational axis. The cam journal causes the cover to open and close when the handle is rotated. The actuation member may include a main journaled portion extending along a common axis that defines the rotational axis and that is separated by an offset cam journal. The chamber in one of the base housing and cover may include cutouts that receive the main journaled portions. The cutouts may be positioned to align the rotational axis parallel to the longitudinal axis.
In accordance with at least one alternative embodiment, the actuation member includes a rotating lever and a sliding cam. The rotating lever is rotatable about a rotational axis to drive the sliding cam in a direction perpendicular to the longitudinal axis. The sliding cam drives the cover along the longitudinal axis. The actuation member engages the cover at multiple points evenly distributed along a width of the cover between the sides of the cover thereby spreading actuation force over a wide surface area of the cover.
In accordance with yet a further alternative embodiment, the actuation member includes a handle and a leg rotatable about the rotational axis. The leg includes threads engaging corresponding threads in at least one of the cover and base housing. The leg drives the cover between open and closed positions as the handle is rotated. The actuation member may include one or more threaded shafts located near the rear end of the base housing and evenly distributed between sides of the base housing. The threaded shaft causes the cover to move when the shaft is rotated.